Establishment of a new breeding procedure based on rice gene targeting using information of molecular genetics and attempt to generate a new variety.

为了利用基因靶向（GT）技术选育水稻新品种，采用正负选择的方法对OsRac1基因进行了修饰，获得了抗稻瘟病菌的水稻。由于G19V在OsRac1上的替换在随机转基因水稻中显示出了有效的免疫效果，因此对原OsRac1位点进行了相同的修饰。G19V替代后，残留在OsRac1位点的阳性标记被Cre-loxP介导的无标记系统去除。在分离的纯合子系的基因修饰的水稻植株中，由于外显子1的G到T的交替，检测到OsRac1的激活，但在植株中也发现了意想不到的生长抑制。在抗砷水稻选育方面，获得了16个具有PvACR的水稻株系。

For generation of a rice new variety by gene targeting (GT) procedure, the OsRac1 was modified by GT based on positive-negative selection to generate blast fungus resistance rice. Since the G19V substitution in OsRac1 had shown the effective immunity in random transgenic rice, the same modification at the original OsRac1 locus was examined. Following to GT for G19V substitution positive-marker remained in the OsRac1 locus was removed by Cre-loxP mediated marker free system. The OsRac1 activation was detected in the gene-modified rice plants of segregated homozygous lines for the G to T alternation in the exon 1, however, unexpected growth inhibition in the plants was also associated. For generation of arsenic resistant rice, the 16 of rice plant lines having PvACR were obtained.